CMOS RF switch device and method for biasing the same

ABSTRACT

Disclosed are CMOS-based devices for switching radio frequency (RF) signals and methods for biasing such devices. In certain RF devices such as mobile phones, providing different amplification modes can yield performance advantages. For example, a capability to transmit at low and high power modes typically results in an extended battery life, since the high power mode can be activated only when needed. Switching between such amplification modes can be facilitated by one or more switches formed in an integrated circuit and configured to route RF signal to different amplification paths. In certain embodiments, such RF switches can be formed as CMOS devices, and can be based on triple-well structures. In certain embodiments, an isolated well of such a triple-well structure can be provided with different bias voltages for on and off states of the switch to yield desired performance features during switching of amplification modes.

PRIORITY CLAIM

This application claims the benefit of priority under 35 U.S.C. §119(e)of U.S. Provisional Patent Application No. 61/352,330, entitled“Circuits & Systems,” filed Jun. 7, 2010, which is hereby incorporatedherein by reference in its entirety to be considered part of thisspecification.

BACKGROUND

1. Field

The present disclosure generally relates to the field of electronics,and more particularly, to systems and methods for configuring andoperating semiconductor switches for processing of radio frequency (RF)signals.

2. Description of the Related Art

In many electronic devices, radio frequency (RF) signal is amplified forprocessing. In wireless RF devices such as cellular phones, suchamplification can facilitate transmission of RF signals at differentoutput powers. Such a capability can enhance a wireless device'soperating time by conserving power usage when permitted (e.g., when thedevice is close to a cell) and increasing the power output only whenneeded (e.g., when the device is far from a cell).

In many situations involving switching between two or more power outputsettings, RF signals can be routed to different power amplifiers to beamplified with different gains. It is desirable that such switching ofRF signals, as well as the amplification process itself, have certainperformance characteristics.

SUMMARY

In certain embodiments, the present disclosure relates to a circuit foramplifying radio frequency signals, the circuit includes a first circuitconfigured to amplify a radio frequency (RF) signal so as to provide afirst gain. The circuit further includes a second circuit configured toamplify the RF signal so as to provide a second gain. The circuitfurther includes a switch having source and drain, a gate between thesource and the drain, and a first well formed about the source anddrain. The circuit further includes a control component configured tocontrol application of first and second bias voltages to the first well,with the first and second bias voltages for the first well beingdifferent and corresponding to the first and second states of theswitch, respectively. In certain embodiments, at least the switch isformed as a complementary metal oxide semiconductor (CMOS) device.

In various embodiments, the control component is further configured tocontrol application of first and second gate bias voltages thatcorrespond to the first and second states of the switch, respectively.In some embodiments, the first state of the switch results in the RFsignal being amplified by the first circuit, and the second state of theswitch results in the RF signal being amplified by the second circuit.

In a number of embodiments, the switch further includes a second wellconfigured to substantially isolate the first well from thesemiconductor substrate. In certain embodiments, the first and secondwells are parts of a triple-well CMOS structure.

In accordance with several embodiments, each of the first and secondcircuits includes one or more power amplifiers, and the switch isconnected in series to the one or more power amplifiers of the firstcircuit such that the first and second states of the switch correspondto ON and OFF states of the switch, respectively. In certainembodiments, the first gain provided by the one or more power amplifiersof the first circuit is lower than the second gain provided by the oneor more power amplifiers of the second circuit. In certain embodiments,the first and second bias voltages for the first well are selected forthe ON and OFF states of the switch so as to provide the circuit with adesirable linearity when providing both first and second amplificationgains.

According to some embodiments, at least one of the one or more poweramplifiers of the first circuit is formed on the CMOS substrate. Incertain embodiments, at least one of the one or more power amplifiers ofthe second circuit is formed on the CMOS substrate.

In some embodiments, a CMOS die can include the foregoing circuit. Incertain embodiments, a multi-chip module can include the foregoingcircuit. In certain embodiments, a wireless device can include theforegoing circuit. In certain embodiments, the wireless device includesa cellular phone.

In certain embodiments, the present disclosure relates to a tangiblecomputer-readable medium having stored thereon computer-executableinstructions that, if executed by one or more computing devices, causethe one or more computing devices to perform operations. Theinstructions include determining whether to amplify a radio frequency(RF) signal by a first gain or a second gain. The first gain isachievable by a first circuit having one or more power amplifiers andconfigured to be turned on or off by a triple-well CMOS switch having anisolated well about the switch's source, gate, and drain, the switch inthe on state resulting in the RF signal being amplified by the firstgain, and the switch in the off state resulting in the RF signal beingamplified by the second gain. The instructions further include applyingor inducing application of a first bias voltage to the isolated wellupon determination that the RF signal is to be amplified by the firstgain. The instructions further include applying or inducing applicationof a second bias voltage to the isolated well upon determination thatthe RF signal is to be amplified by the second gain. The first andsecond bias voltages to the isolated well are different.

In accordance with a number of embodiments, the instructions furtherinclude applying or inducing application of a first bias voltage to thegate upon determination that the RF signal is to be amplified by thefirst gain, and applying or inducing application of a second biasvoltage to the gate upon determination that the RF signal is to beamplified by the second gain.

In various embodiments, the first bias voltage to the isolated well issubstantially equal to a bias voltage applied to the source and thedrain when the switch is on. In certain embodiments, the first biasvoltage applied to the gate is held at a substantially fixed amountabove the first bias voltage applied to the isolated well. In certainembodiments, the substantially fixed amount includes a quantity that isN times a threshold voltage value, where the quantity N is a positiveinteger. In certain embodiments, the second bias voltage to the isolatedwell is substantially equal to the second bias voltage applied to thegate.

According to some embodiments, the isolated well is coupled to thesource and drain such that the bias voltage applied to the isolated wellsubstantially tracks a bias voltage applied to the source and drain. Incertain embodiments, the bias voltage applied to the source and drain issubstantially equal to a voltage provided by a supply that is poweringthe first and second circuits such that the bias voltage applied to theisolated well substantially tracks the supply voltage even when thesupply voltage changes.

In certain embodiments, the present disclosure relates to a radiofrequency switch having a first-type silicon substrate and a second-typeisolation well formed in the substrate. The switch further includes afirst-type isolated well separated from the substrate by the isolationwell. The switch further includes source and drain disposed in theisolated well. The switch further includes a gate disposed on theisolated well so as to allow switching on and off of electricalconduction between the source and drain by application of different biasgate voltages. The switch further includes and/or is under control of abias voltage control component electrically connected to the gate, theisolated well, and the isolation well. The bias voltage controlcomponent is configured to facilitate application of the different gatevoltages for on and off states of the switch. The bias voltage controlcomponent is further configured to facilitate application of differentbias voltages to at least one of the isolated well and the isolationwell for the on and off states of the switch.

In various embodiments, the first-type is a p-type and the second-typeis an n-type. In certain embodiments, the isolation well includes anN-well and a deep N-well, such that in combination with the isolatedwell, the N-well and the deep N-well form a triple-well structure in thesilicon substrate. In certain embodiments, the gate includes a gateterminal and an oxide layer between the gate terminal and the isolatedwell so as to form a CMOS structure.

In some embodiments, the bias voltage control component includes avoltage distribution component configured to distribute the differentbias voltages to the at least one of the isolated well and the isolationwell based on the on or off state of the switch.

In certain embodiments, the present disclosure relates to a method forcontrolling amplification radio frequency signals. The method includesdetermining whether to amplify a radio frequency (RF) signal by a firstgain or a second gain, with the first gain achievable by a first circuithaving one or more power amplifiers and configured to be turned on oroff by a triple-well CMOS switch having an isolated well about theswitch's source, gate, and drain. The switch in the on state results inthe RF signal being amplified by the first gain, and the switch in theoff state results in the RF signal being amplified by the second gain.The method further includes applying or inducing application of a firstbias voltage to the isolated well upon determination that the RF signalis to be amplified by the first gain. The method further includesapplying or inducing application of a second bias voltage to theisolated well upon determination that the RF signal is to be amplifiedby the second gain. In certain embodiments, the first and second biasvoltages to the isolated well are different.

In certain embodiments, the present disclosure relates to a system foramplifying radio frequency signals. The system includes a means foramplifying a radio frequency (RF) signal so as to provide first andsecond gains. The system further includes a means for switching acomplementary metal oxide semiconductor (CMOS) switch between first andsecond states, with the switch having source and drain, a gate betweenthe source and the drain, and a first well formed about the source anddrain. The switch is configured to be capable of being in the first andsecond states so as to facilitate the amplification of the RF signal bythe first and second gains. The system further includes a means forcontrolling the application of the first and second gate bias voltages,and to further control application of first and second bias voltages tothe first well, with the first and second bias voltages for the firstwell being different and corresponding to the first and second states ofthe switch, respectively.

In certain embodiments, the present disclosure relates to a circuit foramplifying radio frequency signals. The circuit includes a first circuitconfigured to amplify a radio frequency (RF) signal so as to provide afirst gain, and a second circuit configured to amplify the RF signal soas to provide a second gain. The circuit further includes a switchhaving source and drain, a gate between the source and the drain, and afirst well formed about the source and drain. The first well iselectrically coupled to at least one of the source and the drain suchthat the first well is at an electrical potential that is substantiallyfixed relative to an electrical potential of the at least one of thesource and the drain. The circuit further includes a control componentconfigured to control application of first and second bias voltages tothe at least one of the source and the drain so as to yield first andsecond bias voltages for the first well that substantially track thefirst and second bias voltages for the at least one of the source andthe drain. The first and second bias voltages for the first well can bedifferent and correspond to the first and second states of the switch,respectively. In certain embodiments, at least the switch is formed as acomplementary metal oxide semiconductor (CMOS) device.

In various embodiments, the control component is further configured tocontrol application of first and second gate bias voltages thatcorrespond to the first and second states of the switch, respectively.In some embodiments, the first state of the switch results in the RFsignal being amplified by the first circuit, and the second state of theswitch results in the RF signal being amplified by the second circuit.

In some embodiments, the electrical potential of the first well issubstantially the same as the electrical potential of the at least oneof the source and the drain. In certain embodiments, the electricalpotential of the source is substantially the same as the electricalpotential of the drain.

In a number of embodiments, the first well is electrically coupled tothe at least one of the source and the drain via an inductor chokehaving one its ends connected to the at least one of the source and thedrain. In certain embodiments, the other end of the inductor choke isconnected directly to the first well. In certain embodiments, the otherend of the inductor choke is connected indirectly to the first well by acharge pump.

In some embodiments, the first well is part of a triple-well CMOSstructure.

In accordance with several embodiments, each of the first and secondcircuits includes one or more power amplifiers, and the switch isconnected in series to the one or more power amplifiers of the firstcircuit such that the first and second states of the switch correspondto ON and OFF states of the switch, respectively.

According to some embodiments, a CMOS die can include the foregoingcircuit. In certain embodiments, a multi-chip module can include theforegoing circuit. In certain embodiments, a wireless device can includethe foregoing circuit. In certain embodiments, the wireless deviceincludes a cellular phone.

In various embodiments, the first and second bias voltages to the atleast one of the source and the drain of the switch is substantially thesame as a voltage supplied by a battery for the cellular phone.

In certain embodiments, the present disclosure relates to a tangiblecomputer-readable medium having stored thereon computer-executableinstructions that, if executed by one or more computing devices, causethe one or more computing devices to perform operations. Theinstructions include determining whether to amplify a radio frequency(RF) signal by a first gain or a second gain, with the first gainachievable by a first circuit having one or more power amplifiers andconfigured to be turned on or off by a triple-well CMOS switch having anisolated well about the switch's source, gate, and drain. The switch inthe on state results in the RF signal being amplified by the first gain,and the switch in the off state results in the RF signal being amplifiedby the second gain. The instructions further include applying orinducing application of a first bias voltage to the isolated well upondetermination that the RF signal is to be amplified by the first gain.The instructions further include applying or inducing application of asecond bias voltage to the isolated well upon determination that the RFsignal is to be amplified by the second gain. In certain embodiments, atleast the first bias voltage to the isolated well is substantially fixedrelative to a bias voltage applied to at least one of the source anddrain of the switch.

In various embodiments, the bias voltage applied to the at least one ofthe source and drain of the switch is substantially the same as a supplyvoltage. In certain embodiments, the supply voltage is applied to bothof the source and drain of the switch. In certain embodiments, the firstbias voltage to the isolated well is substantially equal to the biasvoltage applied to the source and the drain when the switch is on.

In accordance with a number of embodiments, the instructions furtherinclude applying or inducing application of a first bias voltage to thegate upon determination that the RF signal is to be amplified by thefirst gain, and applying or inducing application of a second biasvoltage to the gate upon determination that the RF signal is to beamplified by the second gain. In certain embodiments, the first biasvoltage applied to the gate is held at a substantially fixed amountabove the first bias voltage applied to the isolated well. In certainembodiments, the substantially fixed amount includes a quantity that isN times a threshold voltage value, where the quantity N is a positiveinteger.

In certain embodiments, the present disclosure relates to a radiofrequency switch having a first-type silicon substrate and a second-typeisolation well formed in the substrate. The switch further includes afirst-type isolated well separated from the substrate by the isolationwell. The switch further includes source and drain disposed in theisolated well. The switch further includes a gate disposed on theisolated well so as to allow switching on and off of electricalconduction between the source and drain by application of different biasgate voltages. The isolated well is electrically coupled to a supplysuch that a bias voltage applied to the isolated well is substantiallyfixed to a voltage provided by the supply.

According to some embodiments, the first-type is a p-type and thesecond-type is an n-type. In certain embodiments, the isolation wellincludes an N-well and a deep N-well, such that in combination with theisolated well, the N-well and the deep N-well form a triple-wellstructure in the silicon substrate. In certain embodiments, the gateincludes a gate terminal and an oxide layer between the gate terminaland the isolated well so as to form a CMOS structure. In certainembodiments, the bias voltage bias voltage supplied to the isolated wellis substantially the same as the voltage provided by the supply.

In certain embodiments, the present disclosure relates to a method forcontrolling amplification radio frequency signals. The method includesdetermining whether to amplify a radio frequency (RF) signal by a firstgain or a second gain. The first gain is achievable by a first circuithaving one or more power amplifiers and configured to be turned on oroff by a triple-well CMOS switch having an isolated well about theswitch's source, gate, and drain, with the switch in the on stateresulting in the RF signal being amplified by the first gain, and theswitch in the off state resulting in the RF signal being amplified bythe second gain. The method further includes applying or inducingapplication of a first bias voltage to the isolated well upondetermination that the RF signal is to be amplified by the first gain.The method further includes applying or inducing application of a secondbias voltage to the isolated well upon determination that the RF signalis to be amplified by the second gain. In certain embodiments, at leastthe first bias voltage to the isolated well is substantially fixedrelative to a bias voltage applied to at least one of the source anddrain of the switch.

In certain embodiments, the present disclosure relates to a system foramplifying radio frequency signals. The system includes a means foramplifying a radio frequency (RF) signal so as to provide first andsecond gains. The system further includes a means for switching acomplementary metal oxide semiconductor (CMOS) switch between first andsecond states. The switch includes source and drain, a gate between thesource and the drain, and a first well formed about the source anddrain. The switch is configured to be capable of being in the first andsecond states so as to facilitate the amplification of the RF signal bythe first and second gains. The system further includes a means forcontrolling application of first and second bias voltages to the atleast one of the source and the drain so as to yield first and secondbias voltages for the first well that substantially track the first andsecond bias voltages for the at least one of the source and the drain.In certain embodiments, the first and second bias voltages for the firstwell is different and correspond to the first and second states of theswitch, respectively.

In certain embodiments, the present disclosure relates to a circuit foramplifying radio frequency signals. The circuit includes a first circuitconfigured to amplify a radio frequency (RF) signal so as to provide afirst gain, and a second circuit configured to amplify the RF signal soas to provide a second gain. The circuit further includes a switchhaving a source and a drain, a gate between the source and the drain, afirst well formed about the source and drain, and a second well formedabout the first well. The circuit further includes a voltagedistribution component configured to provide different bias voltages toat least one of the first and second wells. In certain embodiments, atleast the switch is formed as a complementary metal oxide semiconductor(CMOS) device.

In various embodiments, the switch is configured to be capable of beingin first second states by application of first and second gate biasvoltages, respectively. In some embodiments, the first state of theswitch results in the RF signal being amplified by the first circuit,and the second state of the switch results in the RF signal beingamplified by the second circuit.

In accordance with some embodiments, the first and second wells areparts of a triple-well CMOS structure. In certain embodiments, thevoltage distribution component is further configured provide the firstand second gate bias voltages. In certain embodiments, the voltagedistribution component is configured to provide different bias voltagesfor the first and second states of the switch to each of the first andsecond wells. In certain embodiments, the voltage distribution componentis further configured to pass through at least one input bias voltage asa single output. In certain embodiments, the voltage distributioncomponent is further configured to provide the different bias voltagesbased on an input control logic signal.

According to a number of embodiments, each of the first and secondcircuits includes one or more power amplifiers, and the switch isconnected in series to the one or more power amplifiers of the firstcircuit such that the first and second states of the switch correspondto ON and OFF states of the switch, respectively. In certainembodiments, the first gain provided by the one or more power amplifiersof the first circuit is lower than the second gain provided by the oneor more power amplifiers of the second circuit. In certain embodiments,the first and second bias voltages for the first well are selected forthe ON and OFF states of the switch so as to provide the circuit with adesirable linearity when providing both first and second amplificationgains.

In some embodiments, at least one of the one or more power amplifiers ofthe first circuit is formed on the CMOS substrate. In certainembodiments, at least one of the one or more power amplifiers of thesecond circuit is formed on the CMOS substrate.

In a number of embodiments, a CMOS die can include the foregoingcircuit. In certain embodiments, a multi-chip module can include theforegoing circuit. In certain embodiments, a wireless device can includethe foregoing circuit. In certain embodiments, the wireless deviceincludes a cellular phone.

In certain embodiments, the present disclosure relates to a tangiblecomputer-readable medium having stored thereon computer-executableinstructions that, if executed by one or more computing devices, causethe one or more computing devices to perform operations. Theinstructions include determining whether to amplify a radio frequency(RF) signal by a first gain or a second gain. The first gain isachievable by a first circuit having one or more power amplifiers andconfigured to be turned on or off by a triple-well CMOS switch having anisolated well about the switch's source and drain, and an isolation wellabout the isolated well, with the switch in the on state resulting inthe RF signal being amplified by the first gain, and the switch in theoff state resulting in the RF signal being amplified by the second gain.The instructions further include generating a control signal forapplication of bias voltages to the switch. In certain embodiments, thecontrol signal is formatted so as to allow application of different biasvoltages for the on and off states of the switch to at least one of theisolated and isolation wells.

In various embodiments, the instructions further include applying orinducing application of a bias voltage for the on state of the switch tothe at least one of the isolated and isolation wells upon determinationthat the RF signal is to be amplified by the first gain.

According to some embodiments, the instructions further include applyingor inducing application of a bias voltage for the off state of theswitch to the at least one of the isolated and isolation wells upondetermination that the RF signal is to be amplified by the second gain.

In a number of embodiments, the control signal is further formatted toallow application of different bias voltages for the on and off statesof the switch to the gate.

In certain embodiments, the present disclosure relates to a radiofrequency switch having a first-type silicon substrate and a second-typeisolation well formed in the substrate. The switch further includes afirst-type isolated well separated from the substrate by the isolationwell. The switch further includes source and drain disposed in theisolated well. The switch further includes a gate disposed on theisolated well so as to allow switching on and off electrical conductionbetween the source and drain by application of different bias gatevoltages. The switch further includes and/or is coupled to a voltagedistribution component electrically connected to the gate and at leastone of the isolated and isolation wells. The voltage distributioncomponent is configured to provide different bias voltages for the onand off states of the switch to at least one of the isolated andisolation wells.

According to some embodiments, the first-type is a p-type and thesecond-type is an n-type. In certain embodiments, the isolation wellincludes an N-well and a deep N-well, such that in combination with theisolated well, the N-well and the deep N-well form a triple-wellstructure in the silicon substrate. In certain embodiments, the gateincludes a gate terminal and an oxide layer between the gate terminaland the isolated well so as to form a CMOS structure.

In certain embodiments, the present disclosure relates to a method forcontrolling amplification radio frequency signals. The method includesdetermining whether to amplify a radio frequency (RF) signal by a firstgain or a second gain. The first gain is achievable by a first circuithaving one or more power amplifiers and configured to be turned on oroff by a triple-well CMOS switch having an isolated well about theswitch's source and drain, and an isolation well about the isolatedwell, with the switch in the on state resulting in the RF signal beingamplified by the first gain, and the switch in the off state resultingin the RF signal being amplified by the second gain. The method furtherincludes generating a control signal for application of bias voltages tothe switch, with the control signal formatted so as to allow applicationof different bias voltages for the on and off states of the switch to atleast one of the isolated and isolation wells.

In certain embodiments, the present disclosure relates to a system foramplifying radio frequency signals. The system includes a means foramplifying a radio frequency (RF) signal so as to provide first andsecond gains. The system further includes a means for switching acomplementary metal oxide semiconductor (CMOS) switch between first andsecond states. The switch includes source and drain, a gate between thesource and the drain, and a first well formed about the source anddrain. The switch is configured to be capable of being in the first andsecond states so as to facilitate the amplification of the RF signal bythe first and second gains. The system further includes a means fordistributing different bias voltages for the first and second states ofthe switch to at least one of the first and second wells.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the inventions have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment of the invention.Thus, the invention may be embodied or carried out in a manner thatachieves or optimizes one advantage or group of advantages as taughtherein without necessarily achieving other advantages as may be taughtor suggested herein.

The present disclosure relates to U.S. patent application Ser. No.12/844,246, filed on Jul. 27, 2010, entitled “HIGH LINEARITY CMOS RFSWITCH PASSING LARGE SIGNAL AND QUIESCENT POWER AMPLIFIER CURRENT,” nowU.S. Pat. No. 8,369,805, and U.S. patent application Ser. No.12/844,640, filed on Jul. 27, 2010, entitled “VOLTAGE DISTRIBUTION FORCONTROLLING CMOS RF SWITCH,” now U.S. Pat. No. 8,368,463, each herebyincorporated by reference herein in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts a power amplifier module for amplifying aradio frequency (RF) signal.

FIG. 2 schematically depicts an example wireless device that can haveone or more of the power amplifier modules of FIG. 1 configured toprovide one or more functionalities as described herein.

FIGS. 3A and 3B show example system architectures that can beimplemented in the wireless device of FIG. 2.

FIGS. 4A and 4B schematically depict an example of how an RF signal to apower amplifier can be switched ON or OFF.

FIG. 5 shows that in certain embodiments, the switch depicted in FIGS.4A and 4B can be formed as a triple-well CMOS device.

FIG. 6 shows an example configuration for operating the triple-well CMOSswitch of FIG. 5.

FIG. 7 shows that in certain embodiments, a switch bias controlcomponent can be configured to provide desired bias voltages to one ormore portions of the triple-well CMOS switch of FIG. 6.

FIG. 8 schematically depicts an example situation where the switch biascontrol component can control a triple-well CMOS switch for routing RFsignals for amplification.

FIGS. 9A and 9B schematically depict an example of how the amplificationof RF signals can include first and second paths having first and secondgains.

FIG. 10 shows that in certain embodiments, one or more terminals of thetriple-well CMOS switch can be provided with more than one selected biasvoltages for different states of the switch.

FIGS. 11A and 11B show that in certain embodiments, bias voltagesapplied to the gate and P-well of the triple-well CMOS switch can bedifferent for ON and OFF states.

FIG. 12 shows a process that can be implemented to achieve the differentgate and P-well voltages for different switch states.

FIG. 13 shows a process that can be a more specific example of theprocess of FIG. 12.

FIGS. 14A and 14B show that in certain embodiments, bias voltagesassociated with the P-well, source and drain can be coupled so as tochange substantially together.

FIG. 15 schematically depicts an example biasing circuit that can beconfigured to achieve the biasing configuration of FIGS. 14A and 14B.

FIGS. 16A and 16B show more specific examples of the biasing circuit ofFIG. 15.

FIG. 17 shows a process that can be implemented so as to provide thevoltage coupling between the P-well and at least one of the source anddrain terminals.

FIG. 18 shows that in certain embodiments, a process can be implementedso as to yield a gate bias voltage that is above a P-well bias voltageby a selected amount.

FIG. 19 shows a process that can be implemented to obtain the selectedvoltage difference amount of FIG. 18.

FIG. 20 shows that in certain embodiments, various applications of biasvoltages to the triple-well CMOS switch can be facilitated by a voltagedistribution component.

FIGS. 21A and 21B show examples of how the voltage distributioncomponent of FIG. 20 can be configured and controlled.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The headings provided herein, if any, are for convenience only and donot necessarily affect the scope or meaning of the claimed invention.

Provided herein are various non-limiting examples of devices and methodsfor facilitating amplification of a radio frequency (RF) signal. FIG. 1schematically depicts a power amplifier module (PAM) 10 that can beconfigured to achieve such an amplification of the RF signal so as toyield an output RF signal. As described herein, the power amplifiermodule can include one or more power amplifiers (PA).

FIG. 2 schematically depicts a device 11, such as a wireless device, forwhich one or more power amplifiers controlled by one or more features ofthe present disclosure can be implemented. The example wireless device11 depicted in FIG. 2 can represent a multi-band and/or multi-modedevice such as a multi-band/multi-mode mobile phone.

By way of examples, Global System for Mobile (GSM) communicationstandard is a mode of digital cellular communication that is utilized inmany parts of the world. GSM mode mobile phones can operate at one ormore of four frequency bands: 850 MHz (approximately 824-849 MHz for Tx,869-894 MHz for Rx), 900 MHz (approximately 880-915 MHz for Tx, 925-960MHz for Rx), 1800 MHz (approximately 1710-1785 MHz for Tx, 1805-1880 MHzfor Rx), 1900 MHz (approximately 1850-1910 MHz for Tx, 1930-1990 MHz forRx). Variations and/or regional/national implementations of the GSMbands are also utilized in different parts of the world.

Code division multiple access (CDMA) is another standard that can beimplemented in mobile phone devices. In certain implementations, CDMAdevices can operate in one or more of 900 MHz and 1900 MHz bands.

One or more features of the present disclosure can be implemented in theforegoing example modes and/or bands, and in other communicationstandards. For example, 3G and 4G are non-limiting examples of suchstandards.

In certain embodiments, the wireless device 11 can include a transceivercomponent 13 configured to generate RF signals for transmission via anantenna 14, and receive incoming RF signals from the antenna 14. It willbe understood that various functionalities associated with thetransmission and receiving of RF signals can be achieved by one or morecomponents that are collectively represented in FIG. 2 as thetransceiver 13. For example, a single component can be configured toprovide both transmitting and receiving functionalities. In anotherexample, transmitting and receiving functionalities can be provided byseparate components.

Similarly, it will be understood that various antenna functionalitiesassociated with the transmission and receiving of RF signals can beachieved by one or more components that are collectively represented inFIG. 2 as the antenna 14. For example, a single antenna can beconfigured to provide both transmitting and receiving functionalities.In another example, transmitting and receiving functionalities can beprovided by separate antennas. In yet another example, different bandsassociated with the wireless device 11 can be provided with one or moreantennas.

In FIG. 2, one or more output signals from the transceiver 13 aredepicted as being provided to the antenna 14 via one or moretransmission paths 15. In the example shown, different transmissionpaths 15 can represent output paths associated with different bandsand/or different power outputs. For example, two example poweramplifiers 17 shown can represent amplifications associated withdifferent power output configurations (e.g., low power output and highpower output), and/or amplifications associated with different bands.

In FIG. 2, one or more detected signals from the antenna 14 are depictedas being provided to the transceiver 13 via one or more receiving paths16. In the example shown, different receiving paths 16 can representpaths associated with different bands. For example, the four examplepaths 16 shown can represent quad-band capability that some wirelessdevices are provided with.

FIG. 2 shows that in certain embodiments, a switching component 12 canbe provided, and such a component can be configured to provide a numberof switching functionalities associated with an operation of thewireless device 11. In certain embodiments, the switching component 12can include a number of switches configured to provide functionalitiesassociated with, for example, switching between different bands,switching between different power modes, switching between transmissionand receiving modes, or some combination thereof. Various non-limitingexamples of such switches are described herein in greater detail.

FIG. 2 shows that in certain embodiments, a control component 18 can beprovided, and such a component can be configured to provide variouscontrol functionalities associated with operations of the switchingcomponent 12, the power amplifiers 17, and/or other operatingcomponent(s). Non-limiting examples of the control component 18 aredescribed herein in greater detail.

FIG. 2 shows that in certain embodiments, a processor 20 can beconfigured to facilitate implementation of various processes describedherein. For the purpose of description, embodiments of the presentdisclosure may also be described with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products. It will be understood that each block of theflowchart illustrations and/or block diagrams, and combinations ofblocks in the flowchart illustrations and/or block diagrams, may beimplemented by computer program instructions. These computer programinstructions may be provided to a processor of a general purposecomputer, special purpose computer, or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing the actsspecified in the flowchart and/or block diagram block or blocks.

In certain embodiments, these computer program instructions may also bestored in a computer-readable memory (19 in FIG. 2) that can direct acomputer or other programmable data processing apparatus to operate in aparticular manner, such that the instructions stored in thecomputer-readable memory produce an article of manufacture includinginstruction means which implement the acts specified in the flowchartand/or block diagram block or blocks. The computer program instructionsmay also be loaded onto a computer or other programmable data processingapparatus to cause a series of operations to be performed on thecomputer or other programmable apparatus to produce a computerimplemented process such that the instructions that execute on thecomputer or other programmable apparatus provide steps for implementingthe acts specified in the flowchart and/or block diagram block orblocks.

FIGS. 3A and 3B show non-limiting examples of system architectures thatcan include one or more features of the present disclosure. For thepurpose of description, the example architectures are depicted with twoRF bands; however, it will be understood that other numbers of RF bandsare also possible. For example, system architectures having similarfunctionalities can be implemented in configurations having more thantwo bands (e.g., quad-band) or a single-band configuration.

In one example architecture 22, a first RF input indicated as “LB IN”and corresponding to a first band (e.g., a low band) can be amplified byone or more power amplifiers disposed and/or formed on a die 24 a. Suchamplified output RF signal is indicated as “LB OUT,” and can besubjected to impedance matching (e.g., to approximately 50Ω) by acomponent depicted as 30 a. Similarly, a second RF input indicated as“HB IN” and corresponding to a second band (e.g., a high band) can beamplified by one or more power amplifiers disposed and/or formed on adie 24 b. Such amplified output RF signal is indicated as “HB OUT,” andcan be subjected to impedance matching by a component depicted as 30 b(e.g., to approximately 50Ω).

In certain embodiments, amplification for a given RF band can includetwo or more amplification modes. For the example low RF band, the RFinput LB IN can be routed to a high power amplification mode or alow/medium power amplification mode via a switch depicted as 32 a. Ifthe switch 32 a is set for the high power mode, the RF signal canundergo amplification by one or more power amplifiers (e.g., by stagedamplifiers 29 a and 29 b) so as to yield a high power output. If theswitch 32 a is set for the low/medium power mode, the RF signal canundergo amplification by one or more power amplifiers.

In certain embodiments, the switch 32 a need not be employed. Forexample, the input impedance of the staged amplifiers 29 a and 30 a canbe substantially matched, and the RF input LB IN can be provided to bothstaged amplifiers 29 a and 30 a.

In the example shown, a low power mode can be achieved by utilizing apower amplifier 30 a; and a medium power mode can be achieved byamplifying the RF signal in stages by the power amplifier 30 a and asecond power amplifier 30 b. Examples of switching and routing of the RFsignals to allow selection of the low, medium and high power operatingmodes are described herein in greater detail. The low/medium amplifiedoutput RF signal can be subjected to impedance matching by a componentdepicted as 31 a prior to being output in a manner similar to that ofthe high power output signal.

Similarly, for the example high RF band, the RF input HB IN can berouted to a high power amplification mode or a low/medium poweramplification mode via a switch depicted as 32 b. If the switch 32 b isset for the high power mode, the RF signal can undergo amplification byone or more power amplifiers (e.g., by staged amplifiers 29 c and 29 d)so as to yield a high power output.

If the switch 32 b is set for the low/medium power mode, the RF signalcan undergo amplification by one or more power amplifiers. In theexample shown, a low power mode can be achieved by utilizing a poweramplifier 30 c; and a medium power mode can be achieved by amplifyingthe RF signal in stages by the power amplifier 30 c and a second poweramplifier 30 d. Examples of switching and routing of the RF signals toallow selection of the low, medium and high power operating modes aredescribed herein in greater detail. The low/medium amplified output RFsignal can be subjected to impedance matching by a component depicted as31 b prior to being output in a manner similar to that of the high poweroutput signal.

In the example architecture 22 depicted in FIG. 3A, operation of the lowand medium power modes can be facilitated by switch assemblies 27 a, 28a (for the low band) and 27 b, 28 b (for the high band). To operate in alow or medium power mode, for the low band, the switch 28 a can beclosed, and the switch 32 a can be in a state that routes the LB INsignal to the power amplifier 30 a. To operate in a medium power mode, aconnecting switch (depicted as the upper one in the switch assembly 27a) can be closed and a bypass switch (depicted as the lower one) can beopened, such that the power amplifiers 30 a and 30 b amplify the LB INsignal in stages to yield the medium power output. To operate in a lowoutput mode, the connecting switch of the switch assembly 27 a can beopened and the bypass switch of the switch assembly 27 a can be closed,such that the LB IN signal is amplified by the power amplifier 30 a bybypasses the power amplifier 30 b so as to yield the low power output.Operation of low or medium power mode for the high band can be achievedin a similar manner utilizing the switch assemblies 27 b and 28 b.

In the example configuration 22 shown in FIG. 3A, various switches(e.g., 27 a, 27 b, 28 a, 28 b) are depicted as being part of a die 23.In certain embodiments, the die 23 can also include a power amplifierbias control component 25. The PA bias control component 25 is depictedas controlling the example PAs (29 a, 29 b, 30 a, 30 b of the low bandportion, and 29 c, 29 d, 30 c, 30 d of the high band portion) via biascontrol lines depicted as 33 a and 33 b. In certain embodiments, the PAbias control component 25 can be provided with one or more input controlsignals 26 so as to facilitate one or more functionalities associatedwith various PAs as described herein.

In certain embodiments, various switches and power amplifiers associatedwith the dies depicted as 24 a, 24 b can be fabricated on substratessuch as gallium arsenide (GaAs) utilizing devices such as pseudomorphichigh electron mobility transistors (pHEMT) or bipolar field effecttransistors (BiFET). In certain embodiments, the dies depicted as 24 a,24 b in FIG. 3A can be formed on the same GaAs substrate, or on separateGaAs substrates. Further, functionalities associated with the diesdepicted as 24 a, 24 b can be formed on a single die, or on separatedies.

In certain embodiments, various switches (e.g., 27 a, 27 b, 28 a, 28 b)associated with operation of various PAs (e.g., 29 a, 29 b, 30 a, 30 bof the low band portion, and 29 c, 29 d, 30 c, 30 d of the high bandportion) can be fabricated as complementary metal-oxide-semiconductor(CMOS) devices. In certain embodiments, at least some of the PA biascontrol component 25 can be implemented on a CMOS die. In the exampleshown in FIG. 3A, the switches (e.g., 27 a, 27 b, 28 a, 28 b) and the PAbias control component 25 are depicted as being parts of the same CMOSdie 26. In certain embodiments, such switches and PA bias controlcomponent can be parts of different CMOS dies.

In certain embodiments, at least one power amplifier and one or moreswitches associated with its operation can be implemented on a CMOS die.FIG. 3B shows an example architecture 34 that can generally providedual-band signal amplification functionalities similar to that describedin reference to FIG. 3A. In FIG. 3B, “IN 1” and “OUT 1” can representthe low band input and output LB IN and LB out; and “IN 2” and “OUT 2”can represent the high band input and output HB IN and HB OUT. Further,switching functionality associated with switches 32 a and 32 b can beprovided by switches 37 a and 37 b. For high power mode of operation,PAs 29 a, 29 b, 29 c, 29 d that are parts of dies 36 a, 36 b can besimilar to the dies 24 a, 24 b described in reference to FIG. 3A.

In FIG. 3B, power amplifiers 38 a, 38 b, 38 c, 38 d corresponding to themedium/low power modes are depicted as being formed on the same die 35(e.g., CMOS die) on which the switches (e.g., 27 a, 27 b, 28 a, 28 b)are formed. Other than these components being on the same CMOS die,operation of the example medium/low power modes can be achieved in amanner similar to those described in reference to FIG. 3A.

Similar to FIG. 3A, the example configuration 34 of FIG. 3B includes aPA bias control component 37 that is part of the example CMOS die 35.The PA bias control component 37 is depicted as receiving one or moreinput control signals 28 and controlling one or more functionalitiesassociated with the various PAs. The PAs (e.g., 29 a, 29 b for the firstband, and 29 c, 29 d for the second band) associated with the high powermode are depicted as being controlled via bias control lines 39 a and 39b. The PAs (e.g., 38 a, 38 b for the first band, and 38 c, 38 d for thesecond band) associated with the medium/low mode are depicted as beingcontrolled via bias control lines 39 c and 39 d.

It will be understood that the configurations 22 and 34 of FIGS. 3A and3B are specific examples of design architectures that can beimplemented. There are a number of other configurations that can beimplemented utilizing one or more features of the present disclosure.

In the context of switches for RF power amplifiers, FIGS. 4A and 4Bshows a switching configuration 40 that can form a basis for morecomplex architectures. In a signal path configuration 40 a of FIG. 4A,an RF signal can be routed through a first path 42 a by providing aswitch S1 that is closed. In the configuration 40 a, second path 42 b isdepicted as having a switch S2 that is open and a power amplifier. Thus,for the purpose of operating the power amplifier in the example path 42b, the configuration 40 a can represent an OFF state.

In a signal path configuration 40 b of FIG. 4B that can represent an ONstate for the power amplifier, the switch S2 on the second path 42 b isclosed and the switch S1 on the first path 42 a is open. For the purposeof description of FIGS. 4A and 4B, the first example path 42 a isdepicted without any component other than the switch S1. It will beunderstood that there may be one or more components (e.g., one or morepower amplifiers) along the first path 42 a.

In the context of power amplifiers that can be included in portableand/or wireless devices (e.g., mobile phones), a power amplifier systemcan be subjected to varying processes and operating conditions such asvoltage and temperature variations. For example, a power amplifiersystem can be powered using a variable supply voltage, such as a batteryof a mobile phone.

In certain situations, it can be important for a power amplifier systemto switch between power modes so that the power amplifier switch cancontrol power consumption. For example, in a mobile device embodiment,having a plurality of power modes allows the power amplifier to extendbattery life. Control signals, such as mode input signals received on apin or pad, can be used to indicate a desired mode of operation. Thepower amplifier system can include a plurality of RF signal pathways,which can pass through power amplification stages of varying gain.Switches can be inserted in and/or about these pathways, and switchcontrol logic can be used to enable the switches and power amplifiersassociated with the selected power amplifier RF signal pathway.

Placing a switch in a signal path of a power amplifier (e.g., in theexample signal path 42 b of FIGS. 4A and 4B) can produce a number ofeffects. For example, insertion of a switch into a RF signal pathway canresult in a loss of signal power due to radiation and resistive losses.Additionally, even a switch in an OFF state placed along an active RFsignal pathway can attenuate a RF signal. Thus, it can be important thatthe switch introduce low insertion loss in both ON and OFF states.Furthermore, it can be important that the switch be highly or acceptablylinear, so as to reduce distortion of a RF signal which passes throughthe switch. Distortion can reduce the fidelity of an RF signal; andreduction of such distortion can be important in a mobile systemembodiment.

In certain embodiments, switches can be integrated on a mixed-transistorintegrated circuit (IC) having power amplification circuitry, such as aBiFET, BiCMOS die employing silicon or GaAs technologies. Additionally,switches can be provided on a discrete die, such as a pHEMT RF switchdie, and can be configured to interface with a mixed-transistor poweramplifier die to implement a configurable power amplifier system.However, these approaches can be relatively expensive and consumesignificant amounts of area as compared to a silicon CMOS technology.Power consumption and the area of a power amplifier system can beimportant considerations, such as in mobile system applications. Thus,there is a need for employing a CMOS switch in a RF signal poweramplifier system.

In certain embodiments, CMOS RF switches can be relatively large, sothat the switch resistance in an ON-state can be relatively small so asto minimize RF insertion loss. However, large CMOS RF switches can haveundesirable parasitic components, which can cause significant leakagesand cause damage to RF signal fidelity. Additionally, the wells andactive areas of the CMOS RF switches can have associated parasitic diodeand bipolar structures. Without proper control of the wells of a CMOS RFswitch, parasitic structures may become active and increase the powerconsumption of the power amplifier system and potentially render thesystem dysfunctional. Furthermore, CMOS devices are susceptible tobreakdown, such as gate oxide breakdown, and other reliability concerns,so it can be important to properly bias a CMOS RF switch duringoperation.

In certain embodiments, one or more switches described herein can beselectively activated depending on a variety of factors, including, forexample, a power mode of the power amplifier system. For example, in ahigh power mode a CMOS RF switch may be positioned in an OFF state andconfigured to be in a shunt configuration with the active RF signalpath. The isolated P-well voltage of such a switch can be controlled toboth prevent overvoltage or other stress conditions which may endangerthe reliability, while optimizing or improving the linearity of theswitch. The linearity of the RF signal pathway having a shunt CMOSswitch in an OFF-state can be improved by keeping the isolated P-wellvoltage at a selected voltage (e.g., relatively low voltage) so as toavoid forward biasing of parasitic diode structures formed between theP-well and the N-type diffusion regions of the source and drain. Bypreventing the forward-biasing of parasitic diode structures, theinjection of unintended current into the active RF signal pathway can beavoided, thereby increasing linearity of the power amplifier system.

In certain embodiments, some or all of the foregoing example propertiescan be addressed by one or more features associated with a CMOS RFswitch, such as a switch 50 depicted in FIG. 5. The example switch 50can include a triple-well structure having an N-well 52 and a P-well 53formed on a P-type substrate 51. As shown in FIG. 5, the N-well 52 cansurround the P-well 53 so as to electrically isolate the P-well 53 fromthe substrate 51. The N-well 52 can be formed by using, for example, adeep N-well or any other suitable N-type buried layer.

The switch 50 further includes a source terminal 56 and a drain terminal59. An oxide layer 65 is disposed on the P-well 53, and a gate 58 isdisposed on top of the oxide layer 65. An N-type source diffusion regionand an N-type drain diffusion region corresponding to the source anddrain terminals (56, 59) are depicted as regions 57 and 60,respectively. In certain embodiments, formation of the triple-wellstructure and the source, drain and gate terminals thereon can beachieved in a number of known ways.

In certain operating situations, an input signal can be provided to thesource terminal 56. Whether the switch 50 allows the input signal topass to the drain terminal 59 (so as to yield an output signal) can becontrolled by application of bias voltages to the gate 58. For example,application of a first gate voltage can result in the switch 50 being inan “ON” state to allow passage of the input signal from the sourceterminal 56 to the drain terminal 59; while application of a second gatevoltage can turn the switch 50 “OFF” to substantially prevent passage ofthe input signal.

In certain embodiments, the switch 50 can include a P-well terminal 54connected to the P-well 53 by a P-type diffusion region 55. In certainembodiments, the P-type diffusion region 55 and the N-type diffusionregions 57 and 60 can be all formed substantially in the P-well 53. Incertain embodiments, the P-well terminal 54 can be provided with one ormore voltages, or held at one or more electrical potentials, tofacilitate controlling of an isolated voltage of the P-well. Examples ofsuch P-well voltages are described herein in greater detail.

In certain embodiments, the switch 50 can include an N-well terminal 61connected to the N-well 52 by an N-type diffusion region 62. In certainembodiments, the N-type diffusion region 62 can be formed substantiallyin the N-well 52. In certain embodiments, the N-well terminal 61 can beprovided with one or more voltages, or held at one or more electricalpotentials, to provide the switch 50 with one or more desired operatingperformance features. One or more examples of such N-well voltages aredescribed herein in greater detail.

In certain embodiments, the switch 50 can include a P-type substrateterminal 63 connected to the P-type substrate 51 and having a P-typediffusion region 64. In certain embodiments; the P-type diffusion region64 can be formed substantially in the P-type substrate 51. In certainembodiments, the P-type substrate terminal 63 can be provided with oneor more voltages, or held at one or more electrical potentials, toprovide the switch 50 with one or more desired operating performancefeatures. One or more examples of such N-well voltages are describedherein in greater detail.

In the example CMOS device shown in FIG. 5, the switching functionalityof the switch 50 is generally provided by an NMOS transistor defined bythe N-type diffusion regions (57, 60) in the P-well 53. FIG. 6 showsthat for such a configuration, diodes can form at p-n junctions of thetriple well structure. For example, a diode 72 can have an anode formedfrom the P-well 53, and a cathode formed from the N-type diffusionregion 57. Similarly, a diode 73 can have an anode formed from theP-well 53 and a cathode formed from the N-type diffusion region 60.Depending on the voltage of the P-well 53 relative to the voltages ofthe N-type diffusion regions 57 and 60, the diodes 72 and 73 can bebiased in, for example, a reverse bias or forward bias region ofoperation. For the purpose of description herein, bias voltages appliedto the N-type diffusion regions 57 and 60 (corresponding to the sourceand drain terminals, respectively) may or may not be the same. Further,for the purpose of description herein, a reverse bias can include aconfiguration where a voltage associated with an N-type region is equalto or greater than a voltage associated with a P-type region that formsa p-n junction with the N-type region.

In certain embodiments, the N-type diffusion regions 57 and 60 can beheld at substantially the same DC voltage. In certain embodiment, such aconfiguration can be achieved by providing a relatively large valueshunt resistor (e.g., polysilicon resistor) 75 across the source and thedrain.

In the context of triple-well CMOS devices, the N-well 52 cansubstantially isolate the P-well 53 from the P-type substrate 51. Incertain embodiments, the presence of the N-well 52 between the P-well 53and the P-type substrate 51 can result in two additional diodes. Asshown in FIG. 6, the illustrated triple well structure can include adiode 71 having an anode formed from the P-well 53 and a cathode formedfrom the N-well 52. Similarly, the triple well structure can include adiode 70 having an anode formed from the P-type substrate 51 and acathode formed from the N-well 52.

In certain embodiments, the switch 50 can be operated so as toreverse-bias one or more of the diodes shown in FIG. 6. To maintain suchreverse-biases, the source terminal, drain terminal, gate terminal,P-well terminal, N-well terminal, P-substrate terminal, or anycombination thereof, can be provided with one or more voltages, or heldat one or more electrical potentials. In certain embodiments, suchvoltages or electrical potentials can also provide one or moreadditional functionalities that can improve the performance of theswitch 50. Non-limiting examples of such performance enhancing featuresare described herein in greater detail.

Although FIGS. 5 and 6 have described an NMOS transistor as providingthe functionality of a switch, a PMOS transistor can also be employed.

Performance of a silicon CMOS switch such as a triple-well CMOS switchcan be affected by electrical potentials of various parts of the switch.For the purpose of description, it will be understood that a voltage ata given location refers to a difference in electrical potential betweenthe given location and a reference (e.g., a system ground). Thus, itwill also be understood that providing of a voltage can include asituation where a desired electrical potential is held so as to yield adesired potential relative to a reference.

FIG. 7 shows a switch biasing configuration 100, where various voltagescan be applied to different parts of a triple-well CMOS switch. Incertain embodiments, a reference voltage can be provided to an input(102) and an output (104) of the switch. In certain embodiments, thereference voltage provided to the source (input 102) and drain (output104) can be a battery voltage (e.g., approximately 4.2 V for certainlithium-ion batteries). It will be understood that other input andoutput terminal voltage values are possible. Further, input and outputterminal voltages may or may not be the same.

In certain embodiments, gate bias voltage can be controlled by a controlcomponent 114. Similarly, P-well, N-well, and P-substrate bias voltagescan be controlled by components 112, 116, and 118, respectively. For thepurpose of description, bias voltage control functionalities provided bythe components 112, 114, 116 and 118 are sometimes collectively referredto as a switch bias control component 110. It will be understood thatsuch bias voltage controlling functionalities can be achievedindividually, in some combination of one or more control components, ortogether by a single integrated control component.

In certain embodiments, various voltages applied to the triple-well CMOSswitch can be selected so as to maintain the reverse-bias configurationof the various diodes (e.g., 70, 71, 72, 73) formed at various p-njunctions. For example, if the P-substrate portion is held at groundpotential, following voltages can maintain the desired reverse-bias ofthe diodes:

TABLE 1 Approx. voltage (ON state) Approx. voltage (OFF state)P-substrate 0 0 N-well 11.8 11.8 P-well 4.2 1.4 Source/Drain 4.2 4.2Gate 7.0 1.4

As described herein in reference to FIGS. 4A and 4B, a givenamplification mode can be implemented by switching ON and OFF a pathassociated with one or more power amplifiers associated with that mode.Based on such path-switching features, FIG. 8 schematically depicts asimilar switching configuration for an example dual mode amplificationcircuit 120 configured to receive an input RF signal (RF_(IN)) andoutput an amplified RF signal (RF_(OUT)). It will be appreciated thatthe amplification circuit can include one or more additional pathscorresponding to one or more additional power modes.

For the purpose of description, Path 1 can represent a first power mode,and Path 2 can represent a second power mode. For example, Path 1 canrepresent a medium-power (e.g., PAs 38 a and 38 b in FIG. 3B) orlow-power mode (e.g., PA 38 a in FIG. 3B), and Path 2 can represent ahigh-power mode (e.g., 29 a and 29 b in FIG. 3B). Similarly, whenswitching between low and medium power modes, Path 1 can represent alow-power mode, and Path 2 can represent a medium-power mode.

For the purpose of description, FIG. 8 shows a first assembly 126 of afirst switch 122 and a first power amplifier 124 corresponding to thefirst path (Path 1). A second assembly corresponding to the second path(Path 2) is simply depicted as a block 128, and may or may not havesimilar switch and power amplifier. It will be understood that the firstand second assemblies 126, 128 may or may not be on the same die. Incertain embodiments, at least the first assembly 126 can be formed on aCMOS die. In certain embodiments, at least the first switch 122 can beformed on a CMOS die. In certain embodiments, the first switch 122 canbe a triple-well CMOS switch.

As shown in FIG. 8, the power mode associated with Path 1 can beactivated when the first switch 122 is in its ON state (S_(on)). In sucha state, the input RF signal is transmitted through Path 1 via input andoutput switch terminals (102, 104) being closed, and amplified by thefirst power amplifier 124. When the first switch 122 is in its OFF state(S_(off)), the input RF signal is shunted to Path 2 for the second powermode operation.

FIG. 8 shows that in certain embodiments, various voltage biasingcontrol for the switch 122 can be controlled by the switch bias controlcomponent described in reference to FIG. 7. Various non-limitingexamples of such voltage controls are described herein in greaterdetail.

FIGS. 9A and 9B show an example where the first and second power modescan represent low and high power modes, respectively. In the context ofcellular phones, having such a low-power/high-power switching capabilitycan provide desirable features such as extended battery life andreducing un-necessary RF power during transmission (e.g., if a cellantenna is nearby).

In FIG. 9A representative of a low-power configuration 130, the switch(not shown) corresponding to the first assembly 126 of Path 1 is ON.Accordingly, an input RF signal is depicted as being amplified with arelatively low gain so as to yield a low gain output RF signal. In thelow-power configuration 130, the second assembly 128 is not amplifyingthe input RF signal (e.g., by having its switch turned OFF). However,there may be quiescent current passing through the second assembly 128of Path 2.

In FIG. 9B representative of a high-power configuration 132, the switch(not shown) corresponding to the first assembly 126 of Path 1 is OFF.Accordingly, an input RF signal is depicted as being shunted to thesecond assembly 128 of Path 2 to be amplified with a relatively highgain so as to yield a high gain output RF signal. In the high-powerconfiguration 132, the first power amplifier (124) of the first assembly126 is not amplifying the input RF signal (e.g., by having the switch122 turned OFF). However, there may be quiescent current passing throughthe switch 122 and/or the first power amplifier 124.

FIG. 10 shows that in certain embodiments, a switch configuration 140can be implemented for a triple-well CMOS switch such as the switch 122described in reference to FIGS. 8 and 9. In the context of the exampleamplification circuit 120 (FIG. 8) and power mode configurations 130,132 (FIGS. 9A and 9B), the switch configuration 140 can includedifferent bias voltages for ON and OFF states of the switch 122 for oneor more of the following: V_(Pw) for P-well bias voltage, V_(G) for gatebias voltage, and V_(Nw) for N-well bias voltage.

In certain embodiments, the P-well bias voltage (V_(Pw)) for thetriple-well CMOS switch 122 can be controlled to have different valuesfor the switch's ON and OFF states. Such different bias voltages can beselected to provide advantageous features such as manufacturability androbustness of the switch, and improved linearity of the amplificationcircuit 120 (e.g., during the high-power mode).

For example, when the amplification circuit 120 is in the high-powermode (132 in FIG. 9B), the triple-well CMOS switch 122 can be in its OFFstate to shunt the RF signal to the high-power path (Path 2). In certainsituations, such shunting of the RF signal can result in limiting orreducing the linearity of the amplification circuit 120 during ahigh-power transmission operation.

To address such an effect, the P-well bias voltage (V_(Pw)) for the OFFstate of triple-well CMOS switch 122 can be selected to be relativelylow or as low as possible to avoid forward bias of either or both of theP-well (53)/N-type diffusion region (57 and/or 60) junction (e.g.,represented by the diode 72 and/or 73 in FIG. 7) and the P-well(53)/N-well (52) junction (e.g., represented by the diode 71). Incertain embodiments, the N-well bias voltage (V_(Nw)) can be selected tobe relatively high so as to facilitate the foregoing avoidance of theforward bias at the P-well/N-well junction.

In certain embodiments, a lower limit of the P-well bias voltage(V_(Pw)) for the OFF state of triple-well CMOS switch 122 can beselected so as to avoid a gate oxide (65 in FIG. 5) and the p-n junctionbreakdown in the CMOS devices as described herein. In certainembodiments, such avoidance of the foregoing breakdown can befacilitated by having the gate bias voltage (V_(G)) lowered when theP-well bias voltage (V_(Pw)) is lowered for the OFF state of triple-wellCMOS switch 122. In certain embodiments, the gate bias voltage (V_(G))can be lowered to be substantially the same as the lowered value for theP-well bias voltage (V_(Pw)).

When the amplification circuit 120 is in the low-power mode (130 in FIG.9A), the triple-well CMOS switch 122 can be in its ON state to directthe RF signal to the low-power path (Path 1). In certain embodiments,the P-well bias voltage (V_(Pw)) can be selected so as to avoid orreduce the body effect of the P-well, to avoid or reduce the likelihoodof gate oxide breakdown, and/or provide a relatively low or acceptableRF switch insertion loss. In certain embodiments, some or all of theforegoing operating parameters can be addressed by selecting the P-wellbias voltage (V_(Pw)) to be substantially the same as that of thesource/drain diffusion regions (57, 60 in FIG. 7).

FIGS. 11A and 11B depict voltage levels for the foregoing example ofselecting the P-well bias voltage (V_(Pw)) for the ON and OFF states ofthe triple-well CMOS switch, and in some situations the gate biasvoltage (V_(G)). For the purpose of this example, it will be assumedthat the P-substrate is held substantially at a system ground; thus, theP-substrate voltage (V_(Ps)) can be substantially zero. Further, it willbe assumed that the N-well bias voltage (V_(Nw)) and the source/drainbias voltages (V_(S) and V_(D)) are held at substantially constantvalues. In certain embodiments, the source/drain bias voltages (V_(S)and V_(D)) are held substantially at a supply voltage (e.g., batteryvoltage) at both ON and OFF states. In certain embodiments, however,some or all of V_(Ps), V_(S) and V_(D) do not need to be constant.

In certain embodiments, the example set of voltages described herein inreference to Table 1 can address some or all of the various operatingfeatures and functionalities described herein in reference to FIGS.7-11. It will be understood that the example operating voltages of Table1 are in the context of a battery voltage being at approximately 4.2volts. Similar relative voltage values can be provided for other systemshaving different battery voltages.

In certain embodiments, a process 150 shown in FIG. 12 can beimplemented to provide the selection of operating voltages depicted byway of examples in FIGS. 11A and 11B. In block 152, first values forV_(Pw) and V_(G) can be provided to a given triple-well CMOS switch ifthe switch is in a first state. In block 154, second values for V_(Pw)and V_(G) can be provided to the switch if the switch is in a secondstate.

In certain embodiments, the first and second states referenced in theprocess 150 of FIG. 12 can represent ON and OFF states of the switch.Accordingly, a process 160 of FIG. 13 can be implemented as a morespecific example of the process 150 of FIG. 12.

In block 162, first values for V_(Pw) and V_(G) can be provided to agiven triple-well CMOS switch for operating the switch in an ON state.In block 164, a second value for V_(Pw) can be selected so as to belower than its first value for operating the switch in an OFF state. Incertain embodiments, a second value for V_(G) can also be selected so asto be lower than its first value for the OFF state. In block 166, therespective selected values of V_(Pw) and V_(G) can be applied to theswitch based on the state of the switch.

In certain embodiments, an amplification circuit such as the circuit 120(FIG. 8) described herein is preferably configured to effectively passrelatively large power amplifier signals (e.g., in the high-power pathsuch as Path 2 in FIG. 9B) as well as quiescent currents (e.g., whenPath 1 of FIG. 9B is in an OFF state). The amplification circuit is alsoconfigured to preferably avoid breakdown limits of one or more CMOSswitches therein, and maintain a desirable level of linearity. Incertain embodiments, such performance features are desirable while thesource/drain voltages are varying due to variations in the supplyvoltage. For example, a supply voltage being provided by a cellularphone battery can decrease or increase. The battery voltage can decreasedue to, for example, general discharging of the battery with use, and/ora decrease in operating temperature. The battery voltage can increasedue to, for example, recharging of the battery, and/or an increase inoperating temperature.

In certain embodiments, the P-well bias voltage (V_(Pw)), and in somesituations the gate bias voltage (V_(G)), for a triple-well CMOS switchcan be controlled to provide one or more of the foregoing performancefeatures. FIGS. 14A and 14B show that in certain embodiments, the P-wellbias voltage (V_(Pw)) can be selected to substantially track or followat least one of the voltages associated with the N-type diffusionregions (e.g., 57 and 60 of FIG. 10) of the source and drain. For thepurpose of description herein, the N-type diffusion regions of thesource and drain can be held at or about the supply (e.g., battery)voltage. Thus, V_(Pw) can be selected to substantially track or followthe supply (e.g., battery) voltage. For the purpose of description, itwill be understood that such tracking or following of the supply voltagecan include configurations where V_(Pw) is substantially the same as thesupply voltage, as well as where V_(Pw) is offset from the supplyvoltage by some substantially fixed amount.

FIG. 14A shows that in certain embodiments, the P-well bias voltage(V_(Pw)) and the gate bias voltage (V_(G)) can be selected to be similarto the example configuration described in reference to FIG. 11B.

FIG. 14B shows that in certain embodiments, the P-well bias voltage(V_(Pw)) can be held to be substantially the same as and tracking V_(S)and V_(D) (which are substantially the same and substantially equal tothe supply voltage) when the switch is in its ON state. Coupling of theP-well bias voltage (V_(Pw)) with the source/drain voltage (V_(S),V_(D)) to provide such tracking of V_(Pw) is depicted by referencenumeral 170; and variation of the supply voltage that results invariation of V_(S) and V_(D) is depicted by reference numeral 172.

In certain embodiments, the gate bias voltage (V_(G)) for the ON switchcan be made to be above the P-well bias voltage (V_(Pw)) by a selectedamount. Such a gate bias voltage can then remain above V_(Pw)substantially by the selected amount even if the supply voltage varies.In such embodiments, the gate bias voltage can also track the supplyvoltage by being offset by the selected amount from V_(Pw) (which cansubstantially track the supply voltage as shown in FIG. 14B). Forexample, the gate bias voltage (V_(G)) can be established with a chargepump that is reference to the varying supply so as to allow V_(G) togenerally follow the supply voltage, and thus the P-well bias voltage(V_(Pw)).

In certain embodiments, the selected amount of difference between V_(G)and V_(Pw) can be designed to be N×V_(ts), where N is a positive integerand V_(ts) represents a threshold voltage value. Accordingly, by simplychanging the multiplier N, a single threshold voltage value can providea desired difference for between V_(G) and V_(Pw) to provide a stronginversion of the NMOS RF switch channel.

FIG. 15 shows that in certain embodiments, a coupling circuit 174 can beconfigured to provide the functionality of coupling the P-well biasvoltage with the source/drain bias voltage. In the example circuit 174,the source and drain terminals are shown to be connected to a referencevoltage V_(ref) that can represent the supply voltage such as a batteryvoltage.

As shown in FIG. 15, the reference voltage can be coupled to the P-wellterminal via a coupling component 176 such that when the switch is ON,the P-well terminal is provided with substantially the same voltage asV_(ref). In certain embodiments, the P-well terminal can be providedwith a different voltage (V_(Pw, OFF)) when the switch is OFF.

In certain embodiments, one or more features associated with FIGS. 14and 15 can be facilitated by removing a direct-current (DC) blockingcapacitance functionality at the switch's source and drain nodes. Such adesign without the capacitive coupling can provide a number ofadvantageous features, including a reduced cost in materials associatedwith amplification circuits.

FIGS. 16A and 16B show non-limiting examples of how the P-well terminalcan be coupled with the switch's source and drain nodes so as to allowV_(Pw) to track the voltage (V_(S), V_(D)) associated with the sourceand drain nodes. In the examples shown in FIGS. 16A and 16B, suchcoupling circuits can be configured to provide the couplingfunctionality without a capacitive coupling component.

In an example coupling circuit 180, the gate can be provided withV_(G, OFF) and V_(G, ON) voltages for OFF and ON states. In certainembodiments, such voltages can be selected as described in reference toFIGS. 14A and 14B.

In certain embodiments, the N-well can be provided with V_(Nw, OFF) andV_(Nw, ON) voltages for OFF and ON states. Although these voltages aresubstantially constant in the various examples disclosed herein, theymay be selected to be different for the OFF and ON states.

In certain embodiments, bias voltages provided to the source and drainterminals from respective supply sources I_(ref, HPM) (via a transistor184) and I_(ref, XPM) (via a transistor 188) can be made to be atsubstantially the same voltage by use of a relatively large shuntresistor 190 across the source and drain.

In FIG. 16A, coupling of such a supply voltage (e.g., battery voltage)to the P-well voltage V_(Pw) can be achieved by directly coupling atleast one of the source and drain nodes to an ON node associated withthe P-well voltage control component 182 via a choke 186 having aninductance of L_(choke). In certain embodiments, such an inductivecoupling can DC couple the ON voltage V_(Pw) with the supply voltage andinhibit or reduce passage of AC components to the P-well.

In FIG. 16A, the OFF state for the P-well bias voltage is depicted asbeing controlled to receive a voltage V_(Pw, OFF). In certainembodiments, such a voltage can be selected and provided as describedherein in reference to FIG. 14A.

In another example coupling circuit 200 shown in FIG. 16B, operations ofthe gate, N-well, and source and drain can be similar to those describedin reference to FIG. 16A. In the circuit 200, however, coupling of thesupply voltage (e.g., battery voltage) to the P-well voltage V_(Pw) canbe achieved indirectly, where a voltage from at least one of the sourceand drain nodes is depicted as passing through a choke 186, but notbeing connected directly to the ON node associated with the P-wellvoltage control component 182. The voltage source for the ON node forthe P-well is depicted as providing V_(Pw, ON) and coupled to the choke(186) output at a location not shown in FIG. 16B. In certainembodiments, such an indirect coupling of the P-well with the supplyvoltage can be achieved by a charge pump (not shown) that is connectedto the ON node for the P-well, and referenced to the varying supply (viathe choke 186).

FIGS. 17-19 show examples of processes that can be implemented toprovide various voltage control functionalities described in referenceto FIGS. 14-16. FIG. 17 shows that in certain embodiments, a process 210can be implemented so as to allow the P-well bias voltage (V_(Pw)) totrack the voltage associated with N-type diffusion regions of the sourceand drain of a triple-well CMOS switch when the switch is ON. In block212, a bias voltage V_(Ndiff) can be provided to the N-type diffusionregions of the source and drain. In block 214, the P-well and the N-typediffusion regions can be coupled so that V_(Pw) substantially tracksV_(Ndiff). Such coupling can be achieved directly or indirectly betweena source/drain node and the ON node associated with the P-well via anon-capacitive coupling such as an inductive choke.

FIG. 18 shows that in certain embodiments, a process 220 can beimplemented so as to allow controlling of the gate bias voltage (V_(G))for a triple-well CMOS switch when the switch is ON. In block 222, avalue for the P-well bias voltage (V_(Pw)) can be obtained. In block224, a value for V_(G) can be made to be above the value of V_(Pw) by aselected amount. In certain embodiments where V_(Pw) substantiallytracks V_(Ndiff), V_(G) can also change with V_(Pw) (based on V_(G)being greater than V_(Pw) by the selected amount) when the source/drainbias voltage (e.g., battery voltage) changes.

FIG. 19 shows that in certain embodiments, a process 230 can beimplemented so as to allow determination of the selected amount ofdifference between V_(Pw) and V_(G). In block 232, a threshold voltagevalue V_(t) can be selected. In block 234, the selected amount ofdifference can be determined by multiplying V_(t) by a positive integerN. In certain embodiments, such a difference N×V_(t) can be added toV_(Pw) so as to obtain the gate bias voltage V_(G).

As described herein, various voltages can be provided to different partsof a triple-well CMOS switch so as to yield one or more performancefeatures. At least some of such voltages can include different valuesfor ON and OFF states of the switch.

FIG. 20 shows that in certain embodiments, one or more bias voltages forcontrolling the operations of a triple-well CMOS switch 250 can befacilitated by a voltage distribution component 242. Such a componentcan be configured to receive one or more input voltages (depicted asarrows 244) and distribute one or more output voltages (depicted asarrows 246) to the switch 250. Such distribution of the input 244 to theoutput 246 can be controlled by a control signal 248.

In certain embodiments, the voltage distribution component 242 can beconfigured to receive one or more voltages from sources such as supply,charge pump, regulator, and/or other analog voltage sources; and alsoreceive digital logic enable signals. In certain embodiments, inputvoltages can have relatively low current to facilitate enabling anddisabling of one or more triple-well CMOS switches in manners that yieldone or more performance features for amplification of RF signals asdescribed herein.

In certain embodiments, the voltage distribution component 242 can beconfigured such that various voltage distribution functionalities can beachieved via components such as level shifters, combinational logiccircuits, transmission gates, and/or voltage buffers. In certainembodiments, design and operation of such components can be achieved bya number of known ways.

FIGS. 21A and 21B show non-limiting examples of how the voltagedistribution component 242 of FIG. 20 can provide voltage distributionfunctionalities to address some of the voltage control circuitsdescribed herein. For example, FIG. 21A shows that in certainembodiments, a voltage distribution component 262 can be configured todistribute and provide bias voltages 266, including those associatedwith ON and OFF states the P-well, gate and N-well. For each of suchswitch parts, changing between ON and OFF output voltages can befacilitated by switch or switch-like functionalities (depicted as 270)associated with the voltage distribution component 262. In certainembodiments, such switching between the ON and OFF output voltages canbe induced by an N-bit logic input signal, where the number of bits Ncan be selected based on the number and/or complexity of the outputvoltages 266.

FIG. 21B shows that in certain embodiments, not all of the inputvoltages need to be switched between ON and OFF values. For example,some example configurations disclosed herein have the N-well held as asubstantially constant value for both ON and OFF states of the switch.Thus, in certain embodiments, the voltage distribution component 262 canbe configured so as to include an output that is a pass-through or basedon a single input. Such a one-to-one mapping between the input and theoutput can be achieved by, for example, providing a fixed signal pathwayor having a switch or switch-like functionality substantially fixed atone state.

Some of the embodiments described herein have provided examples inconnection with wireless devices and/or mobile phones. However, one ormore features described herein can be used for any other systems orapparatus that have needs for switching of RF signals, and moreparticularly, for switching of RF signals to provide differentamplifications.

Such one or more features can be implemented in various electronicdevices. Examples of the electronic devices can include, but are notlimited to, consumer electronic products, parts of the consumerelectronic products, electronic test equipment, etc. Examples of theelectronic devices can also include, but are not limited to, memorychips, memory modules, circuits of optical networks or othercommunication networks, and disk driver circuits. The consumerelectronic products can include, but are not limited to, a mobile phone,a telephone, a television, a computer monitor, a computer, a hand-heldcomputer, a personal digital assistant (PDA), a microwave, arefrigerator, an automobile, a stereo system, a cassette recorder orplayer, a DVD player, a CD player, a VCR, an MP3 player, a radio, acamcorder, a camera, a digital camera, a portable memory chip, a washer,a dryer, a washer/dryer, a copier, a facsimile machine, a scanner, amulti functional peripheral device, a wrist watch, a clock, etc.Further, the electronic devices can include unfinished products.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” The word “coupled”, as generally usedherein, refers to two or more elements that may be either directlyconnected, or connected by way of one or more intermediate elements.Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Wherethe context permits, words in the above Detailed Description using thesingular or plural number may also include the plural or singular numberrespectively. The word “or” in reference to a list of two or more items,that word covers all of the following interpretations of the word: anyof the items in the list, all of the items in the list, and anycombination of the items in the list.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example, whileprocesses or blocks are presented in a given order, alternativeembodiments may perform routines having steps, or employ systems havingblocks, in a different order, and some processes or blocks may bedeleted, moved, added, subdivided, combined, and/or modified. Each ofthese processes or blocks may be implemented in a variety of differentways. Also, while processes or blocks are at times shown as beingperformed in series, these processes or blocks may instead be performedin parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

While certain embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the disclosure. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms; furthermore, various omissions, substitutions and changes in theform of the methods and systems described herein may be made withoutdeparting from the spirit of the disclosure. The accompanying claims andtheir equivalents are intended to cover such forms or modifications aswould fall within the scope and spirit of the disclosure.

What is claimed is:
 1. A circuit for amplifying radio frequency signals,the circuit comprising: a first circuit configured to amplify a radiofrequency (RF) signal so as to provide a first gain; a second circuitconfigured to amplify the RF signal so as to provide a second gain;first and second switches formed as complementary metal oxidesemiconductor (CMOS) devices and each including a source and a drain, agate between the source and the drain, and a first well formed about thesource and drain; and a control component configured to controlapplication of first and second bias voltages to the first well of thefirst switch, the first and second bias voltages for the first well ofthe first switch being different and corresponding to first and secondstates of the first switch, respectively, the control component furtherconfigured to control application of third and fourth bias voltages tothe first well of the second switch, the third and fourth bias voltagesfor the first well of the second switch being different andcorresponding to first and second states of the second switch,respectively, at least the combination of the first state of the firstswitch and the second state of the second switch resulting in the RFsignal being amplified by the first circuit, and at least thecombination of the second state of the first switch and the first stateof the second switch resulting in the RF signal being amplified by thesecond circuit.
 2. The circuit of claim 1 wherein the control componentis further configured to control application of first and second gatebias voltages that correspond to the first and second states of thefirst switch, respectively.
 3. The circuit of claim 2 wherein the firstswitch further includes a second well configured to substantiallyisolate the first well from a semiconductor substrate.
 4. The circuit ofclaim 3 wherein the first and second wells are parts of a triple-wellCMOS structure.
 5. The circuit of claim 2 wherein each of the first andsecond circuits includes one or more power amplifiers, the first switchbeing connected in series to the one or more power amplifiers of thefirst circuit such that the first and second states of the first switchcorrespond to ON and OFF states of the first switch, respectively. 6.The circuit of claim 5 wherein the first gain provided by the one ormore power amplifiers of the first circuit is lower than the second gainprovided by the one or more power amplifiers of the second circuit. 7.The circuit of claim 6 wherein the first and second bias voltages forthe first well of the first switch are selected for the ON and OFFstates of the first switch so as to provide the circuit with a desirablelinearity when providing both first and second amplification gains. 8.The circuit of claim 5 wherein at least one of the one or more poweramplifiers of the first circuit is formed on a CMOS substrate.
 9. Thecircuit of claim 8 wherein at least one of the one or more poweramplifiers of the second circuit is formed on the CMOS substrate.
 10. ACMOS die comprising the circuit of claim
 1. 11. A multi-chip modulecomprising the circuit of claim
 1. 12. A wireless device comprising thecircuit of claim
 1. 13. The wireless device of claim 12 wherein thewireless device comprises a cellular phone.